I'm working on learning javascript. I'm just a beginner on the programming end, but have been doing html/css stuff for about 8 years now.

My question is pretty simple: What the heck version of javascript should i be learning?!?

The books i'm working out of seem to all be using version 1.2 or 1.3, but in looking for reference stuff online, everything seems to be 1.5 oriented, though there's a lot of stuff on versions up to 1.9.

Tried to decipher what I needed from Wikipedia, the ECMA standard, and the Mozilla developer pages, but to no avail.

I'm sure learning the older version gives me a solid foundation, but is there someplace I can find some kind of comparison charts?

Also, what is the newest acceptable version that has the most cross-browser compatibility?

Any input here would be greatly appreciated! Thanks!